Migler's vertical axis wind turbine U.S. Pat. No. 6,926,491 B2, hereby incorporated by reference, discloses a vertical axis wind turbine, in which, when the wind speed becomes excessive it becomes necessary to feather all the sails to prevent damage to the sails. This is accomplished by rotating the sail restraints from the vertical to the horizontal position, so that the sails are free to go into the feathered position. The rotation can be accomplished either by manual means, that is by pulling cables that control the position of the sail restraints, or automatically by operation of motorized sail restraint controllers. The latter method requires the monitoring of the wind speed by an anemometer, control circuitry to take the data from the anemometer and then, if the wind speed is excessive, signal the motorized sail restraint controllers to rotate the sail restraints. Both methods are less than satisfactory. The manual means (pulling the cables) requires human attendance and intervention, while the operation of the motorized sail restraint controllers requires the addition of sensors for wind speed, control circuitry and motors, which add cost and complexity to the device. A third problem is that the resetting of the sail restraints by the motorized sail restraint controllers when the wind speed is reduced to allowable levels could result in some of the sails being trapped in the feathered position, that is, on the “wrong” side of the sail restraints. For the device to become practical these three problems must be solved.
The invention described here solves the three problems described above. First, it eliminates the need for human intervention by the pulling of the cables when the wind speed becomes excessive. Second, it eliminates the necessity for the motorized sail restraint controllers, and its associated wind sensor, control circuitry and motors. Third, it automatically resets the sails into the correct nonfeathered working position when the wind speed eventually returns to allowable levels.